Timing mechanisms have been utilized for decades in the control of many different appliances. The present invention relates generally to electric dryers, and more particularly to a pushbutton hand dryer of the type commonly found in public rest rooms. With such a hand dryer, a user pushes a button or knob to start a drying cycle. During the drying cycle, a timing motor, a heater and a fan are turned on; and at the end of a drying cycle, as determined by the timing motor, the timing motor, heater and fan are automatically turned off. Such dryers must be simple, rugged and durable in construction and operate with great reliability over a long service life. To achieve such features, the hand dryer should have the fewest possible parts that operate in the simplest possible way.
As shown in FIG. 6, with known timer circuits, the heater H and fan motor FM are connected to the two non-neutral lines L1, L2 of a 220 volt ("V") source by a single switch S1. When the switch S1 is open, one side of each of the heater H and fan motor FM is disconnected from one of the non-neutral lines L1; however, the other side of each of the heater H and fan motor FM remain connected to the other of the non-neutral lines L2. Therefore, any inadvertent electrical contact of the one side of the heater and/or fan motor to a ground, for example, the metal dryer housing or base etc., will result in 120 being applied thereto. Thus, the heater H and/or fan motor FM will be operated at half power. Such an inadvertent electrical contact with ground can result from a frayed, nicked or broken wire or other conductor accidently contacting a neutral or ground potential.
Therefore, there is a need to better isolate the heater and fan motor from the non-neutral wires of a power source.